Border Patrol agents smuggling weed and coke. Immigration agents forging documents and robbing drug dealers. TSA employees caught with child porn. Those are just a few of the crimes perpetrated by Department of Homeland Security employees in just the past year.

Since the creation of the Department of Homeland Security nearly a decade ago, the agency’s inspector general has been tasked with uncovering corruption, waste and criminality within its own ranks. The IG has had his hands full.

According to a newly released DHS inspector general’s summary of its significant investigations, 318 DHS employees and contractors were arrested in 2011 (.pdf). That’s about one arrest per weekday of the men and women who are supposed to be keeping the country safe. The report lets us not only see how corrupt some agents tasked with protecting the homeland can be, it also gives us a scale of the problem. In short: There are a lot of dirty immigration and border officers.

That might send the wrong impression. DHS is a massive agency of more than 225,000 employees. Within DHS, sub-agency Customs and Border Protection has more than doubled in recent years to nearly 59,000 employees. Maybe it’s not so surprising an organization of that size has a few bad apples. There’s also some good news. The number of arrests is going down: there were 519 arrests in 2010, compared to the 318 last year. Still, within that number includes some serious crimes.

“Border corruption may take the form of cash bribes, sexual favors, and other gratuities in return for allowing contraband or undocumented aliens through primary inspection lanes or even protecting and escorting border crossings; leaking sensitive law enforcement information to persons under investigation and selling law enforcement intelligence to smugglers; and providing needed documents such as immigration papers,” Charles Edwards, the acting inspector general for DHS, told Congress earlier this month (.pdf).

According to the report, a Border Patrol agent from Tucson named Yamilkar Fierros was given 20 months in prison for providing “sensor location maps, trail maps, and communications technology” to cartel members in exchange for more than $5,000 in bribes. Another incident involved an 8-year veteran CBP agent who conspired with cocaine traffickers to let drugs past his border inspection post. The agent, whose name and former location are undisclosed in the report, was sentenced to 110 months in federal prison.

Other corruption cases read like a list of bad career decisions, some appalling; others involve petty greed. The appalling includes at least two employees — one from CBP and another from the TSA — who were caught in possession of child pornography. A Border Patrol agent in Arizona “punched a fellow agent and threatened him with his service-issued weapon after the fellow agent joked about the excessive amount of tactical gear the [Border Patrol] routinely wore,” according to the report.

An Immigration and Customs Enforcement agent named Valentino Johnson was sentenced to 120 months in prison for working an off-duty job robbing drug dealers, according to the report. Johnson, who was busted after attempting to steal a load of fake cocaine, worked with a stick-up crew who saw him as a means to portray a sense of legitimacy to their robberies.

A Border Patrol agent in Arizona named Michael Atondo was convicted for attempting to distribute marijuana. The agent, according to the report, using his patrol vehicle to bypass checkpoints and smuggle more than 100 kilos of marijuana. Among ICE agents, many cases involve forging fake immigration documents for bribes. A CBP agent posted to Logan International Airport in Boston even reportedly stole astronaut Neil Armstrong’s customs declaration form and attempted to sell it on the internet.

The corruption investigations have also netted contractors. At least one contractor with the Federal Emergency Management Agency was convicted of defrauding the agency of more than one million dollars. A company employee for security contractor MVM was discovered to have falsified training documents to the Federal Protective Service, which oversees security at government buildings.

There’s also a caveat. While the numbers of arrests have fallen this year, the long-term trend of cases against CBP agents, at least, has been on a rise since 2004, according to the Arizona Daily Star. Between 2004 and 2010, the number of cases doubled.